Preheat oven to 200 F. Heat oil to 375 F in a medium pot fitted with deep-fry thermometer. Sift flour, baking powder, salt, and cayenne together in a medium bowl. In a separate bowl, whisk egg, milk, and butter together and stir into dry ingredients. Fold in corn and let batter sit for 5 minutes. Drop heaping tablespoonfuls of batter into heated oil and fry until golden, about 3 minutes (work in batches of 4 or 5). Drain on a baking pan lined with paper towels. Transfer to a second baking pan and keep warm in oven. Serve with yogurt dip (recipe follows).